Android shot past Apple's iOS in market share last month, at least according to the number of ad impressions seen by ad network Chitika.

Chitika found that iOS took the lead in November with 51.7 percent of traffic seen on its ad network, followed by Google with 46.1 percent. But as the holiday season came into full bloom in December, Android grabbed the lead with a 51.6 percent share, leaving iOS in second place with 46.5 percent.

Apple has of course remained a dominant force in the smartphone arena. But it's been getting stung by a nest of Android rivals, including HTC, Motorola, and especially Samsung. Combine the vast number of devices with the surge in demand, and Android continues to scoop up market share.

The open nature of Android itself is also driving growth as device makers have the freedom to offer the mobile OS on a variety of devices and customize the user experience.

"The highly flexible nature of Android in regard to both hardware and software create the conditions necessary for what market leaders in all industries fear most: change," noted Chitika.

Google also continues to build up its Android Market with around 400,000 apps now available. Though Apple has well over 500,000, Google has lately been able to increase the pace at which new apps become available.

Of course, the open nature of Android Market has taken its share of lumps, with many security experts pointing to Google's mobile ecosystem as a favorite target for malware writers. But such openness is also key to attracting developers and consumers alike, says Chitika.

Overall, though, Apple still leads in the number of active iOS devices with 250 million (including the iPhone, iPad, and iPod Touch), compared with Android with 230 million.

About the author

Journalist, software trainer, and Web developer Lance Whitney writes columns and reviews for CNET, Computer Shopper, Microsoft TechNet, and other technology sites. His first book, "Windows 8 Five Minutes at a Time," was published by Wiley & Sons in November 2012.
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